The present invention relates to an apparatus used to combine signals representing at least two physical quantities and provide a single resultant signal. More particularly, the present invention relates to a an apparatus for combining a first output signal proportional to a first measured quantity represented by a difference in signals from a first pair of output terminals with a second output signal proportional to a second quantity represented by a difference in signals from a second pair of output terminals.
Transducers for measuring physical parameters are well known. For example, load cells are commonly used when determining rotational loads and axial loads about or along a reference axis. FIG. 1, discussed further below, schematically illustrates a test apparatus used for imparting forces to a test system that includes, as used herein, a test specimen, a reaction structure and a specimen attachment fixture.
Since it is desirable to obtain the force applied to the test specimen, acceleration compensation is provided to the test system to remove or delete the force required to accelerate the specimen attachment fixture. Commonly, the acceleration signal is transmitted using signal lines that are isolated from the signal lines used to transmit a signal proportional to the force applied by the test system. At a remote location away from the test system the acceleration signal is combined with the force signal to remove the force required to accelerate the attachment fixture and thereby obtain a force signal more representative of the actual force applied to the test specimen.